SCXI-1124 Current amplification

[Ralph@NES]

Hello again

I'm going to be using my SCXI-1124 to turn on and off some 110v accessories.  I have 12v switching 110v relays that apparently need more current than my 1124/1325 can provide (I feel the coil pull a bit but it's not enough to really kick the relay).  What method is best to amplify the current coming out of my 1124?

-Transistor, or

-Use two banks of relays to accomplish this; One small relay which can be triggered at very low current and voltage by the 1124, which will trigger the second bank of relays by using an external power source, or

-Something I haven't come up with yet.

Input?  Thanks!

[Logan_K]

The SCXI-1124 can only sink up to 20mA - do you know how much current your relays require to turn on? For more than 20mA, I would recommended going with programmable switches (such as the SCXI-1163R) with an external power supply - similar to what you mentioned. You may need to put a resistor in series with your power supply to limit the total current to the relays if it does not have a built-in current limiter. If you want to go the discrete component route, there is alot of information out there on relay drivers, and what components you will need to make this work. A discussion on relay drivers is probably too complicated for a forum like this.

-Logan

[Shea_S]

You could use the SCXI-1124 current outputs in parallel to increase the current drive.  Of course this will limit the number of current channels you have to drive the relays.